1. Field of the Invention
The present invention relates to a swivel work machine, such as construction or civil-engineering machinery such as a backhoe, equipped with a dozer device.
2. Description of the Related Art
There exist swivel work machines, such as a backhoe, that are equipped with a dozer device and that are provided with a swivel base on a travel device, an implement arranged in a front part of the swivel base such that the implement can pivot laterally, and a swing cylinder for laterally swinging the implement. Such swivel work machine has the dozer device at the front part of the travel device. The dozer device is provided with a pivot support supported to the travel device to be vertically pivotable, a blade supported to a front end side of the pivot support to be pivotable about an angle pivot shaft extending in a vertical direction, and also about a tilt pivot shaft extending in a fore-and-aft direction, and a dozer cylinder for pivoting the pivot support vertically, an angle cylinder for pivoting the blade about the angle pivot shaft as well as a tilt cylinder for pivoting the blade about the tilt pivot shaft. A dozer lever is provided, and the dozer cylinder is extended and retracted to effect vertical pivoting of the pivot support in correlation with an actuation of the dozer lever. (See for example, JP-A-2005-207195, JP-A-2000-240093, and JP-A-8-270017.)
Among this kind of conventional swivel work machines is a machine that has a dozer lever provided with a button switch and that is configured to extend and retract the dozer cylinder to pivot the pivot support vertically by operating the dozer lever in the fore-and-aft direction, and configured to extend and retract the tilt cylinder to pivot the blade vertically about the tilt pivot shaft by pivoting the dozer lever laterally without depressing the button switch, and to extend and retract the angle cylinder to pivot the blade laterally about the angle pivot shaft by pivoting the dozer lever laterally with the button switch depressed (see for example, JP-A-2005-207195). There are also conventional swivel work machines in which a tilting and an angular pivoting of the blade is selected by an operation switch provided in the control area. There are also machines in which a control knob of the blade lever for causing vertical pivoting of the swing support has an electric 4-way switch for selecting between angular pivoting and tilting operations of the blade, and which are configured such that the output signals from the switches when depressed are sent to an electromagnetic valve located in a hydraulic circuit for switching between the angle cylinder and the tilt cylinder and to an electromagnetic valve for switching between an extension and retraction of the selected valve also located in the hydraulic circuit, to effect lateral angular pivoting and lateral tilting of the blade (See JP-A-2000-240093, JP-A-8-270017).